An instant message and presence service system (hereinafter called an IM&P service system) refers to a system in general that delivers an instant message (hereinafter called an IM) and manages the status of the users. The basic architecture is defined by RFC 2778 (Request for Comments: 2778).
A presence system comprises a presentity that presents its own presence information, a watcher that observes the presence information, and a presence service that receives presence information from the presentity and delivers it to the watcher. A watcher can request the presence service to send a notification when the presence information on some presentity changes.
Combining a presence system, which provides user status information, with an instant message system allows communication to be made considering the status of the other party. (See Patent Document 1)
There are two types of IM&P service systems: one type is implemented as a client-server system, and the other type as a peer-to-peer system in which client terminals are interconnected. In the former type of system, one or more servers are interconnected with client terminals for communication via a network, such as the Internet, to receive presence information from presentities of client terminals, deliver the information to the watches of other client terminals and, at the same time, relay the delivery of instant messages among client terminals. In the latter type of system, the functions of a server in the client server system are installed on client terminals. Although the present invention is applicable to both systems, the following describes an example in which the IM&P service system is implemented as a client server system, for convenience of description.
[Patent Document 1]
Japanese Patent Kokai Publication JP-P2002-183064A
The conventional IM&P service system provides the instant message service basically as a messaging service between two users. Therefore, when a plurality of watchers check the status of one presentity and send an IM to that presentity, the communication between the presentity and each watcher is performed independently. This requires the presentity to interact with the plurality of watchers separately.
Even if the group interaction (chat) function is available, the procedure must be executed to “invite” each participant before starting the group interaction as described in Patent Document 1. That is, even when there are a plurality of watchers having an interest in the particular status of a presentity, there is no means for dynamically grouping the watchers.
In addition, for a user to participate in a group, he or she must be invited by some other user already participating in the group. Therefore, neither a user has a chance to know that there is such a group nor can the user participate in the group voluntarily.